Flying shear



July 12, 1938.

R. J. LEHMANN FLYING SHEAR Filed June 8, 1937 2 Sheets-Sheet l lmzenfm':Ease-ET J LEHMflNN,

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R. J. LEHMANN v FLYING SHEAR July 12, 1938.

Filed June 8, 1937 2 Sheets-Sheet 2 Inventor: /QOBEET J LE'HMflN/V,

Patented July 12, 1938 UNITED STATES PATENT OFFICE FLYING SHEAR RobertJ. Lehmann, Duquesne, Pa. Application June 8, 1937, Serial No. 147,132

. 3 Claims. This invention relates to flying shears of the typeincluding a knife mounted to reciprocate in I the direction of travel ofpassing work to be sheared, this knife being pivoted so that it swings 5free from the work upon completion of its shearing function to permitits'return without marring the work, itbeing understood that such ashear' operates to sever long lengths of material into shorter units;whereby work continues to pass upon the completion of a shear.

One of the objects of the present invention is to positively prevent thework from being marred upper ends swing they move vertically relativeone another. The arms are operated through the medium of a suitably'powered connecting-rod 3. The knife 4 is pivoted at 5 to a cross-head 6which is reciproatively carried by the arm 2 but which connects throughits pivot 5 with the arm I. The arrangement is such that the arm 2 mayreciprocate in the direction of passing work to be sheared, this causingreciprocation of the crosshead 6, and consequently of the knife 4,transversely of this work, because these parts are connected through thepivot 5 with the arm I.

The work W passes through an opening I in the arm 2, the latter fixedlycarrying a knife 8 which opposes the knife 4, the advance of the knife 4toward the knife 8 upon movement of the arms I and 2 in the direction ofthe work, through the medium of the rod 3, serving to shear the work.

The moment the work is sheared the knife 4 is kicked free, and it iswith the problem of keeping this knife free from the work during the'return of the shear to its starting position with which the presentinvention is particularly con cerned. I

. It might be mentioned that in shears of this type the arms I and 2 areso arranged that, as they swing with the work, they move the knife 4diagonally respecting the work between positions where the knife is freefrom the work to one 55 where it shears the work, this shearing beingeffected through the cooperation of. the lower knife 8.

According to the invention, a latch 9 is pivoted to the cross-head 6above the pivot 5, this latch carrying a hard steel block I II on oneend which engages a hard steel block I I fixed to the turning top of theknife 4, upon riding over a cam I2, also fixed to this top and leadingto this block I I. The parts are arranged so that latching occur: whenthe knife swings free from the work upon completion of its shearingoperation.

The end of the latch 9 carrying the block is constantly urged to itsknife-latching position by a spring I3, this being in the form of afiatsteel strip having one end bearing against an appropriate end of thelatch 9 and its other end suitably anchored, as at I4, to the cross-head6.

It is, of course, necessary for the knife to swing back to its normal oroperative position when the arms I and 2 return to their startingposition after a shearing stroke, and this is effected through themedium of a cam I5 which is fixed to the arm 2 paralleling the path ofthe crosshead 5, this cam providing an incline I6 against which anextension H of the latch 9 works, this extension having a hard steelface I8 riding the cam I5. When the face I8 of the extension I I ridesthe cam I5 below the incline I6, the springurged latch 9 is operative.When the face I8 rides the cam I5 above the incline I6, it raises andholds the latch 9 in unlatched position.

Assuming the arms I and 2 to be in their starting position, the face I8will be on the upper part of the cam I5 and, through the extension I'i,will be holding the latch 9 in its unlatched position, the knife 4consequently depending in an operative position. When the rod 3 ispowered to effect a shear, the arms start to move with the work, theknife 4 thereupon shearing the work and being immediately kicked free.40

As previously explained, the knife 4 is moved toward the work throughthe operation of the arms I and 2 and the medium of the cross-head 6. Asthis cross-head 6 moves, the face I8 rides down the incline I6 of thecam I 5 and permits the latch 9 to move to latching position under theurge of the spring I3. Therefore, when the knife 4 is kicked free fromthe work the two blocks I0 and II immediately engage and the knife ispositively held free from the work. The latch 9 remains latched untilthe arms I and 2 return to their, starting position a predeterminedextent, whereupon the latch is moved to unlatching position through itsextension II, the face I8 riding over the incline I 8 of the cam I! atthis time. 1

It will be appreciated that the knife 4 should not be unlatched so thatit can swing to its depending position until the arms I and 2 havereturned to a point where the cross-head 6 is raised so that it holdsthe knife 4 free from the work W. The required timing may be effected ina number of ways, but it is considered preferable'to provide the cam l5with bolt slots 19 through which fas tening bolts 20 are passed, thesebolts securing the cam to the arm 2. This permits the position of thiscam to be adjusted and .so permits timing of the movement of the latchto knife-unlatching position.

Although the-principles of the invention have been disclosed by means ofa specific example in accordance with the patent statutes, it is notintended to thereby limit its scope, except as defined by the followingclaims.

I claim:

1. A flying shear having a knife mounted to reciprocate diagonallyrespecting passing work to be sheared between positions where it is freefrom said work and where it shears said work, said knife moving withsaid work while approaching its second named position and being pivotedto swing free from said work upon completion of its shearing operationto permit its return to its first named position without contacting saidwork, said shear being characterized by including means responsive tosaid knife pivoting free from said work for positively locking itagainst reverse pivoting and means responsive to the return of saidknife a predetermined extent toward its first named position foreffecting unlocking action of the first named means so said knife canreversely pivot.

2. A flying shear including a mounting adapted to reciprocate in thetraveling direction of passing work to be sheared, a knife pivotallycarried by said mounting for reciprocation transversely of said work,said knife shearing said work upon reciprocation theretoward and themovement of said work causing said knife to pivot free therefrom, alatch for latching said knife when pivoted to a work-free position, saidlatch reciprocating with said knife, means for urging said latch to itsknife-latching position, a cam fixed to said mounting and a cam-riderfor said cam, said rider connecting with said latch and reciprocatingwith said knife, said cam and said rider cooperating upon reciprocationof said knife away from said work to move said latch to aknife-unlatching position against the urge of said means.

3. A-flying shear including a mounting adapted to reciprocate in thetraveling direction of passing work to be sheared, a knife pivotally.carried by said mounting for reciprocation transversely of said work,said knife shearing said work upon reciprocationtheretoward and themovement of said work causing said knife to pivot free therefrom, alatch for latching said knife when pivoted to a work-free position, saidlatch reciprocating with said knife, means for urging said latch to itsknife-latching position, a cam fixed to said mounting and a cam-riderfor said cam, said rider connecting with said latch and reciprocatingwith said knife, said cam and said rider cooperating upon reciprocationof said knife away from said work to move said latch to aknife-unlatching position against the urge of said means, and said cambeing movable on said mounting to permit timing of the movement of saidlatch to knife-unlatching position.

ROBERT J. LEHMANN.

